A signal monitor is a device used in traffic control assemblies to detect and respond to conflicting or otherwise improper signals. Such improper signals may arise, for example, due to field signal conflicts, a malfunctioning controller, faulty load switches, cabinet mis-wiring, improper supply voltages, and the like.
When one or more certain critical failures occur, the signal monitor instructs (or causes other components to instruct) the signal lights to enter an emergency “flash” mode, in which the traffic lights on all sides of the intersection generally enter a flashing red state.
It is often the case that certain other events external or internal to the traffic control cabinet occur that should be attended to, but which do not typically require the intersection to enter the flash mode. Such events include, for example, damage to the controller cabinet, problems with the cabinet power supplies, data communications issues, and relatively non-critical signal light conditions (such as faulty “DON'T WALK” signals, minimum green time violations, etc.) Some prior art signal monitors include additional logic outputs that provide more detailed status information to the controller, but such information is only provided in cases where a critical fault has occurred, and the intersection is already in a flash mode.
It is therefore desirable to provide improved signal monitor systems that may be programmed to identify non-critical events and communicate appropriate alarms to the controller based on those events. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.